1. Field of the Invention
This invention relates generally to apparatus for monitoring respiratory activity, which also can include snoring activity, and more particularly to a reusable pyro/piezo transducer for producing an electrical signal proportional to respiratory airflow and/or vibration due to snoring episodes for subjects undergoing sleep studies.
2. Discussion of the Prior Art
Applicant's assignee, Dymedix Corporation of Minneapolis, Minn., has pioneered the development of improved sensors that are adapted to be attached to the upper lip or throat area of a patient that, during sleep, produces an electrical signal proportional to inspiratory and expiratory airflow and to episodes of snoring. In U.S. Pat. No. 5,311,875, applicant first disclosed such a sensor embodying a polyvinylidene fluoride (PVDF) film as the active element of such a respiration activity sensor. The film has both pyroelectric and piezoelectric properties and, as such, is responsive to both temperature changes and physical vibration, producing an electrical signal output that can be signal processed to effectively separate the temperature change induced signal from the signal due to vibration.
Improvements in the sensor are the subject of U.S. Pat. Nos. 6,894,427, 6,551,256, 6,485,432, 6,491,642 and 6,254,545, the teachings of which are hereby incorporated by reference as if set forth in full herein.
For the most part, the sensor construction described in the aforereferenced patents were intended for single-use application in that they would not hold up to repeated cleaning. More particularly, moisture could permeate the layered construction to compromise the electrical interface between the PVDF film and its connection to an electrical lead. Moreover, the handling during cleaning operations would lead to detachment of the lead's contact with the PVDF film.
It is accordingly a principal object of the present invention to provide a respiratory activity sensor especially constructed so as to be reusable. More particularly, the sensor or transducer of the present invention is designed to be moisture impervious and constructed such that lead wire pull-out is no longer a problem.